Small particle in my viewfinder?

Hello,This morning i change lens with my friend,after i fixed back my own lens i discovered a small particle in my viewfinder.I took a blower (without brush) blow inside my camera but that small particle still not removed.I blowed again but the particle still stuck inside my viewfinder.Do you think i did the correct way?I scared i might spoilt the camera's mirror or the sensor or other parts of my camera body.Before i release my lens i got switch off my camera & the blower nose didn't touch any part of the camera body.I am using Nikon D90. Thank you.